I learned this great trick from another calculus teacher, she suggestedbuying those paper wedding bells that are made of tissue paper. If youthink about it they are made of two cardboard pieces and a *honeycomb* ofpaper, which when is spun about and the two cardboard pieces joined theymake a bell. If you buy bells which are large enough you can cut them intomore helpful shapes. I have cut a rectangle form, which generates acylinder, a 1/4 circle, which generates a hemisphere, and a few other ones.Usually, after seeing a few of these the kids begin to understand what isgoing on, and they begin visualizing them without the crutch. Hope thishelps. If you have any questions about what I mean email me.